This application discloses an advanced highly precise temperature measuring probe for use in household electric water kettles including those commonly used to heat water and water containing foods. There is now an increasing interest in heated kettles that can prepare warmed or hot water or other liquids at accurately selected and controlled temperatures. This is important to both tea and coffee drinkers who want to steep the tea or brew the coffee at a carefully selected temperature for optimum extraction and the best tasting beverage. Green teas for example are generally preferred if extracted around 140 degrees Fahrenheit. Black teas are better if brewed near the normal boiling point of water over 200 degrees.
Domestic kettles for heating and boiling water have not been available with a sufficiently precise means to measure or display the water temperature. In recent years one commercial kettle has been offered with a very rudimentary temperature controller that could be set to maintain the water temperature in such kettles, but only within a range which might be as large as ±10 degrees Fahrenheit. These have proven inadequate because their accuracy did not meet the needs of the discriminating tea and coffee drinkers. Generally the connoisseur wants to preset the temperature accurately to ±2° Fahrenheit and to have the water held at the selected temperature until it is convenient to prepare the beverage or food. These inventors are not aware of any commercial household kettle that meets these needs. One of the main reasons that commercially available kettles have failed to provide the necessary accuracy is the lack of a practical compact thermal probe in which to mount a thermal sensor that can sense very accurately the water temperature. There is no shortage of electrical thermocouples, thermostats and other temperature sensors that produce an electrical signal that reflects their temperature with more than needed accuracy and reproducibility. The unfilled need has been for a thermal probe of a practical design to house the sensor that can be placed in physical and thermal contact with the heated liquid, such as water, that is not physically intrusive within the kettle, which is supported in a manner that is not responsive to the ambient air temperature, to the extremely high temperature of the kettle heater, the temperature of its supporting plate or to the temperature of the kettle body and operating parts. All existing thermal probes for kettles known to these inventors were unsatisfactory for one or more of these stated reasons.